As a laser-bonded component and a production method thereof in the related art, there is a method for superposition-bonding of copper plates (for example, refer to PTL 1). A nickel plated film is formed on a surface of a copper plate, and then the plated film is irradiated with laser light so as to bond the superposed copper plates. FIG. 6 is a diagram illustrating a laser-bonded component and a production method thereof that are disclosed in PTL 1.
As shown in FIG. 6, copper plate 12 is disposed on clad material 11. Clad material 11 is a laminated body of copper and a copper-molybdenum sintered body. Nickel plated film 13 is formed on a surface (top face) of copper plate 12. A YAG laser light absorbing rate of nickel is 2.5 times a YAG laser light absorbing rate of copper and a copper alloy. In a case where nickel plated film 13 is irradiated with laser light to weld copper plate 12 to clad material 11, a desired welding state may be obtained with relatively lower laser power and energy compared to a case in which copper plate 12 is irradiated with laser light to weld copper plate 12 to clad material 11.
In addition, FIG. 7 is a diagram illustrating a laser-bonded component and a production method thereof in the related art disclosed in PTL 2. As shown in FIG. 7, an end face of clad material 22 and an end face of clad material 23 come into contact with each other. Both of clad plates 22 and 23 are laminates of high melting point material 24 and low melting point material 25. High melting point material 24 of clad material 22 and high melting point material 24′ of clad material 23 come into contact with each other, and also low melting point material 25 of clad material 22 and low melting point material 25′ of clad material 23 come into contact with each other. Contact portion 28 between high melting point materials 24 and 24′ is irradiated with laser light to weld high melting point materials 24 and 24′, whereby bead portion 26 is formed. Next, contact portion 29 between low melting point materials 25 and 25′ is irradiated with laser light to weld low melting point materials 25 and 25′, whereby bead portion 27 is formed. In this method, weld penetration of high melting point material 24 with low melting point material 25 substantially does not occur. Accordingly, characteristics of clad materials 22 and 23 are maintained in a laser-bonded component obtained by laser bonding (for example, refer to PTL 2).
In addition, as a method in which a first metallic plate and a second metallic plate are superposed, and laser light is emitted from the first metallic plate side to bond the metallic plates each other, there is a known method in which a first plated film is formed on one surface or both surfaces of the first metallic plate, and then a second plated film is formed on one surface or both surfaces of the second metallic plate. Both of the first plated film and the second plated film have a thickness of several μm. In a case where a laser light absorbing rate of the first plated film is higher than a laser light absorbing rate of the second plated film, laser energy may be set to be relatively small. In addition, in a case where a melting point of the first plated film is higher than a melting point of the second plated film, explosion of the first plated film due to the irradiation of laser light is prevented. In a case where the melting point of the second plated film is higher than the melting point of the first plate film, explosion of the second metallic plate due to the irradiation of laser light is prevented (For example, refer to PTL 3 to 6).
In addition, there is a known method in which a cover plate of copper or a copper alloy including a solder film is superposed on a base plate of a copper alloy including a solder film and then the cover plate is irradiated with laser light to bond the members each other is disclosed (for example, refer to PTL 7 and 8).